This work has developed and evaluated a microemulsion-based drilling fluid formulation with characteristics to be applied in oil wells. The microemulsion was formulated with a solution of water/glycerol, pine oil, and Tween 80, a nonionic and biodegradable surfactant. The physical and chemical properties of the drilling fluid obtained in this work were investigated through rheology and filtration analysis, solids content, aging, lubricity, toxicity, and thermal degradation. A non-toxic microemulsion-based drilling fluid oil-in-water (O/W) with high lubricity (0.07638) and thermal stability was obtained with suitable viscosity, gel strength and low fluid loss (4.0 mL), low solids content (6%), stability in a wide range of salinity conditions, and the possibility of high water content (above 85% in mass fraction). The fluid presented a pseudoplastic behavior, and statistically significant Herschel–Bulkley parameters were obtained.

A busca por novas formulações para aditivos lubrificantes em fluidos de perfuração é constante, devido à necessidade da indústria do petróleo e gás de aperfeiçoar produtos e processos e preservar o ecossistema, contribuindo com o desenvolvimento sustentável. O uso de microemulsões na fase upstream é crescente, principalmente na área de recuperação avançada de petróleo, porém inovador na área de perfuração de poços de petróleo. O objetivo deste estudo foi desenvolver e caracterizar microemulsões biodegradáveis e de baixo custo de produção para aplicação como aditivo lubrificante de fluidos de perfuração base água. Para tanto, foram realizados: a) teste de estabilidade nas microemulsões e nos fluidos de perfuração aditivados; b) teste de tamanho de partícula nas microemulsões; c) teste de ponto de turbidez, para avaliação do comportamento da microemulsão quanto a temperatura; e d) teste de lubricidade das microemulsões, do lubrificante proposto e dos fluidos de perfuração aditivados. Os resultados de lubricidade encontrados foram satisfatórios, mostrando que os sistemas microemulsionados avaliados podem ser aplicadas como aditivos lubrificantes biodegradáveis em fluidos de perfuração base água para perfuração de poços de petróleo, causando um menor impacto ambiental.

This study aimed to develop microemulsion through of ternary system composed of brine (aqueous phase), vegetable oil (oil phase), and non-ionic polyethoxylated surfactants, T20 and T80. From the ternary diagrams obtained, two systems were chosen in the regions of microemulsion (Winsor IV) and, subsequently, were conducted rheological study, at different temperatures, and cloud point studies of these systems. The results showed that the microemulsion of T20/brine/vegetable oil presented thermal stability up to 53° C and microemulsions of T80/brine/vegetable oil of 72o C, that could be due a change in micelle morphology and cloud point of each microemulsion system. The rheological results indicated non-Newtonian behavior, adjusted by Herschel - Bulkley model.

Toe-to-Heel Air Injection – THAI™ is an enhanced oil recovery technique that employs in situ combustion combined with technologies for horizontal well drilling, which is unprecedented in Brazilian oilfields. Motivated by this context, this research is intended to studying the application of the THAI™ process in a semisynthetic reservoir, with characteristics similar to those found in Brazil's Northeastern region. At the end, it was demonstrated that the intermittent air injection increased the oil recovery, when compared to the continuous injection, what reinforce the need for further research turned to ongoing and future projects in mature oilfields.